Conventional or rigid body mechanisms comprise rigid links connected by kinematic joints (e.g. hinges, sliding joints, gears, etc.) to transfer motion and force. Unlike rigid body mechanisms, compliant mechanisms derive at least a part of their mobility from the deformation of flexible segments of the mechanism. Fully compliant mechanisms are typically single-piece elastic bodies that derive their mobility entirely from the deformation of the body of the mechanism. Many fully compliant mechanisms include de facto hinges, i.e., regions of the elastic bodies that act as hinges and hence, experience higher strain than surrounding regions. The higher strain in the de facto hinges is achieved in the prior art by having a relatively small cross sectional area in these regions as compared to the surrounding regions. De facto hinges store strain energy during the deformation of the mechanism and are the most common sites for material failure which limits the useful life of the mechanism. The ideas presented in this application also apply to the fully compliant part of a partially compliant mechanism. Hence, in the rest of the application, we will drop the qualifiers: partially or fully.
As used herein, “performance” refers to the force and/or motion transmission properties of a mechanism such as its quasi-static force-deflection behavior, the nature of its deformation, the path traced by a point on the mechanism, its dynamic response, etc. Once a compliant mechanism with a given design is fabricated, its performance in response to a given set of loads is fixed. Therefore, compliant mechanisms often must be custom-designed for each application.